Explain how a bright line is formed by the diffraction grating at the first order diffraction angle

A diffraction grating is basically a series of very small, point-like light sources, where the adjacent ones are always a given distance away. To have a bright line, the light waves from all of the point-like sources must interfere constructively. This happens when the path difference between the adjacent light rays is an integer multiple of the wavelength. Therefore, there will a bright line for all the angles for which the path difference is the 0, the wavelength, twice the wavelength, and so on. Another name for the integer multiple is called the order of diffraction. Hence, at the first order diffraction angle, the path difference between the adjacent rays is exactly the wavelength of the light we use, so the light from each source on the grating will interfere constructively. This results in a bright line. 

AB
Answered by Abel B. Physics tutor

18901 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

What is an ohmic resistor? How to check if a resistor is ohmic?


What is the main evidence for the Big Bang theory?


The Heisenberg Uncertainty principle states that ΔxΔp > h/4π. What is represented by the terms Δx, and Δp? What can we say about p if the precise value of x is known? What does this mean for experimental results.


A source of green laser light has a wavelength of 560nm, what is its frequency? Give your answer to an appropriate number of significant figures and using the correct units.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences